Telephone system



Feb. 28, 1933. w. c. PHEBUS 1,899,105

' TELEPHONE SYSTEM Filed June 30, 1930 2 Sheets-Sheet 2 asp/1mm: LIA/E phone set for use on 1.)

shows, schematically,

PatenteclFeb. 28, 1933 UNITED" STATES] PATENT orrlcr.

r T'ION or DELAWARE Application filed June 30,

'lhisjinvention relates to telephone systems. in general, and while itis concernedparticu larly with systems for supplying telephone Agt'elephone system of the above general disclosed in applicants co-pending'appl"cation,"SerialiNo. l11,714,=filed December 5;1929, on which the present invention may be considered as an improvement. One of the main objects of the inventioni's the provision of new and improved circuits and apparatus for increasing theefliciency of telephone systems of the type mentioned. A

feature in this respect is the arrangement for transposing the single conductor comprising the intermediate talking circuit in order to reduce the eife'ct of inductive disturbances from outside sources.- Another object of the invention is the provision of simple and re-" liable circuits for such systems which will h, operatesaisfactorily with existing signalling and control circuits 'withoutinterfering in any way with the normal functions of such circuits; and which at the same time will be reasonablylnexpenslve to Install and to maintain. I I i The various features including those above I referred to, and others, will be discu'ssed'in detail, reference being had to the accompany- I ing drawings of which Fig.1 shows a tele the operating principle upon which the intermediate circuit is based; and Fig. 3 shows a; section of railroad track equipped Y with the necessary circuits and switching devices for providing telephone service. I

Referringnow to it willbe seen that the telephone set (consists of a receiving amplifier RA and a transmitting amplifier TA; :The' r ceiving amplifier is ofthefour stage resistance coupled type, and is normally connected to a high impedance windmg of the inductor I. Theftransm tting amplifier s arranged with two stagesof amplificationthelatter being of the pushpull type; A separate low impedance winda railroad train; Fig.2

INCL, OF CHICAGO, ILLINOIS, A CORPORA- TELEPHONE sYsTnII '1930. Serial No; 464,792.

ing on the inductor I is arranged to be con- -nected tothe transmitting amplifier by a switching relay controlled by a keyassociated with the transmitter or microphone "The inductor-is also} provided with" a third 7 Winding for testing purposes, this winding beingconnected to a manual-jack by means of whichxan ordinary local battery telephone set may be connected up. The inductor which consists of a laminated" core of soft} WILLIAM CLPHEBUS, oF-BnRwYN, LLINOIS, 'AssIGnonBY MESNE, ASSIGNMENTS," T0 7 ASSOCIATED ELECTRIC LABORATORIES,

, iron provided with the three windings above I referred to is suspended beneath'the locomo-- tive or=one of the cars of' a train so that the two poles are as near as practical to the con ductor 11 which is installed between the rails, sufficient space being allowed so that the inductor will clear any obstruction-likely to be found on the tracks,"

Referring now-to Fig. 2, conductors13" and 14 represent the two sections of a block circuit inductively coupled by the transformer TRS. The'opposite ends of the 'two sections are connected by transformers TR7 and TRQ, respectively, to two telephone sets, which are shown'for convenience as being of the ordinary local battery type. The goons ductors are connected] to non-corresponding terminals of the transformer TR8, the opposite, terminals of which are connected to ground; Thisarrangement gives the effect of a'transposition. I I

Assuming now for example that a power line 12 parallels the circuits in question, cur rent flowing in this line will induce a-similar current in each of the sections of the telephone circuit, The current in the. firstsection will be induced in the second section through the transposing transformerTRS, and will tend to neutralize the current in duceddirectly in the second section from the power line. Voice currents will be transmitted over this circuit in the following'man ner: when the transmitter attelephoneset TEL is'spoken into, the voice currents'induced in" the left-hand winding'of transl former TRTwill be induced inthe right-hand winding of the transformer, and current will 'fiow from ground through this winding, over conductor 13, through the left-hand winding of transformer TR8,to ground; Similar C111? rents will be induced in the right-hand winding of transformer TBS, and thence over conductor 14 and transformer TR9, which connects the line with telephone set TEL1. It will be noted, however, that since the windings of transformer TBS are connected in transposed relationship the direction of current flow in conductor that in conductor 14, as indicated by the arrows. The final result is that voice currents are transmitted with relatively little loss, while interfering currents are cancelledout,

thus producing a relatively quiet talking 'system. This arrangement can be used equally well with ordinary grounded telephone lines or toll lines.

Referring now to Fig. 3, there is shown a section of railroadtrack divided into electrically separate blocks. A block circuit consists of the two track rails across whichthere is bridged a battery at one end and a signal control relay at the other. The relay is normally energized by current flow over the block circuit but becomes deenergized when a train enters the block, as a low resistancecircuit path is completed through the Wheels and axle of the train. The signal relay of each block is shown although only that of each third block is used in connection with the telephone systems comprising the invention. The various relay spring contacts of the block signalling system have no functions to perform in connection with the telephone system and have, therefore, been omitted from the drawings. The spring contacts shown for relays 23 and 27 are additional springs which are installed on existing signal relays for effecting the switching operations to be explained hereinafter. In addition to utilizing' the existing signal relays as above-mentioned, certain of the block circuits are provided with an-additional relay, such as the relay 240:: 28, connected in series with the block signalling battery. This relay is given a relatively still spring adjustment so that it does not become energized in series with the signal control relay, but does becomeenergized from the increased current flowresulting from the entry of a train into the block.

It has been assumed for conveniencethat the railroad, to which the telephone system comprising the invention is being applied, is

already equipped for block signalling. It is obvious that, if this is not the case, the necessary relay and battery equipmentfmay be installed as shown, omitting however the re- 7 lays not concerned with the telephonesystem, such as relays 21, 22, 25 and 26. i

It will be noted that the equipment for block A corresponds to that of block D, block B corresponds to block E, andblock G corresponds to block F. This relationship is carried out throughout the system, each third block being similarly equipped. Each group ofthree sections or blocks is provided with 13 will be opposite to.

an intermediate circuit consisting of a single grounded line. Under certain conditions, to be explained later, two or more intermediate circuits may be connected together. These circuits provide the talking path between the head and rear end of a train, between separate trains, and between a train and the dispatchers line.

The single conductor comprising the intermediate circuit is simply a grounded line provided with a transposing transformer in the middle and with transformers at each end for connecting with adjacent circuits. In theprcferred embodiment shown, an auXiliary path through the rails is provided, since actual operation has shown this arrangement to be particularly reliable. The rail connections may omitted, however, and the ground return alone used, or the rail return maybe used and the ground connection omitted. In either case the operation of the circuit is substantially that of a grounded line, since in actual practice the/track rails are usually more or less heavily grounded. It hasalso beenfound that bridging a condenser, such as C, around the insulating members separating adjacent blocksin the same group has a tendency to increasethe eiiiciency of the system, particularly in dry weather when the resistance of the ground connections increases.

A dispatchers telephone l ne parallels the track and is equipped at convenient intervals with selecting switches,'such as S and S1. These switches, or selectors-as they are commonly called, may be of the general type disclosed in United States patent to Hulit, No. 1,221,801'01 April 1917. The switches are selectively controlled from the dispatchers oflice by means of a sender, such as that shown in the, above referred to Hulit patent, and operate to connect up the various intermediate circuits to the dispatchers line. The dispatchers line will also be equipped with a telephone set, preferably one of the type disclosed in. applieants co-pending application previously referred to.

The selector arrangement permits the dispatcher to obtain connection with a train at will. In order that the train may call the dispatcher, additional connecting apparatus is provided at certain blocks which is adapted to be controlled from the train. Connection with this apparatus is made by means of a shoe and ramp arrangementwhi ch may be of the type commonly used for train control, asdescribed in Bulletin #5 of the American Railway Association Committee on Automatic Train Control, published June, 1929.

Before taking up the description of the will first be described. Consider for example the intermediate circuit for a group comprising blocks C, D and under the assump tion: that the blocks are unoccupied. "Under these conditions relay27, will be energized winding of transformer T1 to ground, and

in parallel therewith through condensers C1 to the rails of section'Dx Inductively connectedwith this circuit by; the transformer T1 is a circuit extending from theicommon ground and rail connection ofblock D, righthand winding of transformer T1, conductor 11,contacts 56 a'nd'62 which short-circuitthe left-hand winding of transformer T3, to ground, and also through condensers C1 to the right-hand end of the rails of Seaman.

It will, be seen from the foregoing that the above circuit is entirely separate 'fromthe adjacent circuits at either end, due to the short-clrcults around the windings of transformers T2 and T3, respectively. The adjacent circuits incidentally-are exactlythe same as the circuit described, as are also the other intermediate circuits of the system.

lVhen block D is occupied by a train, relay 26 will become dee'nergized with no effect on the above described circuit. This relay is used only for the usual block signallingcircuit (not shown). When block E is occupied by a train relay 27 will become deenerv gized and, in addition to performing'its usual block signalling functions which are well known, will remove the short-circuit from the left-hand and right-hand windings of transformer T3 by opening contacts '61 and 62. Relay 27 will also preparealocking' circuit for relay 32 by closing contact '63.

Under the above conditions, theintermediate circuit of blocks 0, D and E and that of the adjacent group including block F willbe in ductively connected by transformer TR3. WVhen block C is occupied relay 24rwillbecome energized to close a pointin the locking circuit of relay 30 which corresponds to relay 32, the utility of which will be described hereinafter. Relay 25, willxbecome deenergized but this relay has no effect on the'intermediate circuit. J a y a j I X NVhen block B is occupied the same conditions areset up asdescribed-forblockvE, that is, the-intermediate circuit of blocksA and B and the preceding block is: inductively connected with the intermediate circuitof blocks C, D. and E by-fthe-transformer T2.

It may be noted at this point that each oftho transformers is connected up to give the effect of a-transposition'as described in connection with Fig. 2. Thus regardless of the number of intermediate circuitsconnec'ted the train will always'bein inductive'rela- I tionship with the same intermediate circuit. The various block circuits will normally be longer than the average train and consequently, there will bean overlapping only when the train leaves one group of blocks and enters theadjacent group, such as in passing from blockB to C. Under these conditions the two intermediate circuits will be joined to form a single circuit, as described.

Itis possible, of course, thatthe block circultsmay be relatively short and that a train Vmay overlap morethan two blocks in which case the intermediatecircuits in (if necessary) three groups of blocks will be inductively connected.

Havingin mind the operation of the tel'e: phone set (Fig.1 1) previously described, it

is clear that 1n operating the transmitter if a train is either standing still or moving through any of the blocks, a current will'be induced. in the intermediate circuit. This current may bepicked upby the inductor of a similar. telephone set: at a point in any of the blocks concerned in the intermediate circuit. For example, in transmitting from a point in block E the voice currents willbe impressed on the intermediate circuit which inclu des'the circuit of blocks C, D and E and those of the adjacent :blocks to the right.

which are connected up by transformer T3.

The currents may be picked'up in either blocks C, D. and E or the threeblocks to the right of E and then amplified. by the receiving amplifier, to operate the associated loud speaker. In this manner communication may be held in bothdircctions from the head end to the :rear end of a train or between patchers; line; Communication may thus be. held between difi erentparts of the train and between trains without interfering with the service over the-dispatchers line.

Should the dispa'tcherdesire to GOIIllnllIlh,

"trains occupying the section of track inquescate with a train, for example,when the train a is occupying block E, as shown, selector S1 will, be operated to close the contacts'associated with theparticular intermediate circuit involved, in this c aseconta-cts 59c and 60,

thereby closing acircuitfor relay'32. Relay 32 on operatingwill complete a lockingcircuit for itself byway of contacts '54 and 63;;

open additional points'in the short circuit for the windings of transformer T3 at contacts 55 and 56, and connect the middle winding of the transformer across. the dispatchers line at contacts 57 and 58. The voice cur rents induced in the intermediate circuit, as previously described, will thus be impressed on the dispatchers line through the transformer T3, and similar currents applied to the dispatchers line will be impressed on the intermediate circuit through this same transformer. This arrangement permits a conversation in both directions as long as the train is in one of the siX blocks concerned The dispatcher will normally allow the selector S1 to remain in its operated position during the conversation, although if this is not done-the circuit will be maintained during the time the train occupies blocks E and F, due to relay 32 locking through contact 63 when block E is occupied or'through contact 64* when block F is occupied.

it will be seen from the foregoing that by m ans of the single selector S1 communications may be established with the train 111 fany one of six blocks, regardless of whether or not block E is occupied. The adjacent imermediate circuits will be connector on the operation of relay 32, which opens the shcit-circuit around the winding of transit'ormer T3, as described. A similar selector S controls the connection of the preceding intermediate circuits to the dispatchers line in the samemanner. V,

In establishing a connection from a train to the dispatchers line, key K is operated and. as the train passes the ramp 48, a circuit is closed from battery" through the contact winding of relay 31, and through the rail and wheel to the other pole ofthe battery. Relay 31 on operating completes a circuit for r lay 32 at contact 53. Relay 32 ener=- gizes and performs the functions previously described, i. e., connects up the adjacent intermediate circuit and connects up the dispatchers line. Relay 32 will remain locked up aslong as the train occupies eitherof blocks E and F, which provides a suflicient interval to hold the usual, conversation. The ramps, such as 47 and 48, may be located at any point along'the blocks B and E, resnectively. In actual practice, however, these ramps will be located near. the right hand end of the' concerned bloclrs in order eliminate the use of long conductors from the snrings'of the ramp relay to the associate, apparatus. I

In order to test the telephone apparatus, the test telephone TT is connected with the test winding of the: inductor by means of the plug P and jack J. With key K3 oper-' voice currents setup in the test wind- 7 when the transmitter isspoken intowill duced in the receiving winding of the c .ctor'and amplified in the usual way. Theitransmitter is tested with key K2 operated. The amplified voice currents ima ground return, for inductively connectin he key, shoe SH, ramp 48, through the -rrninrl return, said conductor being inductr-xcly transposed with respect to ground at point substantially equidistant from the ends thereof, and a telephone set on the train inductively connected. to said circuit.

2. In-a telephone system for communicating between two difierent points on a moving train or between either of said points and a wayside point, the combination, with transmitting and. receiving sets at each point, of an intermediate circuit comprising two inductively connected sections, each of which consis s of a single conductor and said telephone sets.

p 3. In a telephone system for communicating between two different points on a moving train or between either ofsaid points on awayside point, the combination, with transmitting and receiving sets at each point, of an intermediate circuit comprising a single conductor and a ground return.

, said conductor being inductively transposed with respect to ground at apnroxima mid-point thereof, and means incluc I circuit for inductively connecting cl sets.

4:. In a telephone system for communicating between two difi'erentpoints on a moving-train or between either of said points and a wayside point, the combination, with transmitting and receiving sets at each point, of air-intermediate circuit comprising a single conductor and aground return inductively connecting the two sets on the train, and means controlled from the waysidepoint for inductively connecting said circuit with the at that point.

.5. In a telephone system for communicating between different points on a moving train, the combination, with transmitting and receiving sets at each point, of a stationary intermediate circuit comprising a single conductor and a ground return, said conductor being inductively transposed with respect to ground at the midpoint thereof, and means including said circuit for inductively connecting said sets.

6. In a telephone system for communicating between different points on a moving train, the combination, with transmitting and receiving setsat each point, of a plurality of stationary intermediate circuits each comprising a single conductor and a ground return, means controlled by the train a said 1,899,105 r a I for connecting adjacent circuits in transposedrelationship, and means including said connected circuits for inductively connecting said sets. Y

7 In a telephone system for communicating between a moving train and a wayside point, the combination, with a transmitting and receivingset on the train, of a trans mitting and .receiving set at the wayside point, a wayside circuit, a plurality of separate intermediate circuitse'ach comprising a ing between a moving ,trainan'd a wayside point, the combination, with; a transmitting and receiving set on the train, of a transmitting and receiving set at the wayside point,

aplurality of separate intermediate circuits each consisting of a single conductor and a ground return for connecting said sets, and means I for connecting said circuits together in transposed relationship.

9. In a telephone system for communicating between two difierent points on a moving train or between either of said points and a wayside point, the combination, with transmitting and receiving sets at each-point, of a plurality of separate intermediate circuits each comprising a single conductor and a sald sets, and means controlled from the wayside point for inductively connecting adjacent ones of said circuits.

10. The combination, I with a railroad track divided into a plurality of electrically 11. The combination, with a railroad track divided into a plurality of electrically insulated sections, of separate closed electrical circuits each comprising a single conductor and a ground return for similar groups of sections, said circuits'being adapted to inductively connect with a telephone set carried by a train occupying any one of the associated track sections, and means for connect- 7 ing adjacent circuits when adjacent sections of two groups are simultaneously occupied by a train or trains.

12. The combination," with a railroad track divided into a plurality of electrically insulated sections, of separate closed electrical circuits each comprising asingle conductor round return for inductively connecting and a ground return for similar groups of sections, said. circuits beingadapted to inductively connect with a" telephone set carried by a train occupying any'oneof the assoc'iated track sections, and meansautomatically operative when a tram occupies a pa rticular one'of said sections for connecting-the c1rcu1t assoc ated w1th the occupied section with the circuit associated with the adj acent group of sections. I

13. The COlllblIliLilOl'l, with a railroad track divided into a plurality of electrically insulated'sections, ofa separate closed electrical circuit "comprising a single'conductor anda ground return for each group of sections, said circuits being adapted to inductively connect with atelephone set carried by a train occupying anyof the associated track sections, and means'for connecting the circuits of ad ji'ilcent section groups in transposed relations 1 r I V 14.- The combination, with a railroad track divided into a plurality of electrically insulated sections, of a separate closed electrical circuit'comprisinga single conductor and a ground return for each group of sections, said circuitb'eing adapted to inductively connect with a telephone set occupying any of the associated track sections, and means for connecting the circuits-of adjacent section groups so that a current flow in one direction in one circuit will set up a similar current flow in the opposite direction in the other circuit.

15. Inco nbination, an inductor comprising an iron core and three separate windings, a receiver connected to the first winding, a transmitter adapted to be'connected to the second winding, and a test set adapted to be connected to the third win dingfor testing both said receiver and said transmitter.

16. In combination, a receiver inductively connected with a telephone line by a high impedance winding of an inductor, a transof said inductor, and a test set adapted to be inductively connected with either said receiver or said transmitter by a third winding of said inductor.

17. In a system for communicating between a moving train and a wayside point, the combination, with a telephone setat the wayside point, of a line extending from said set along the route followed by the train, a telephone set on the train, a plurality ofseparate intermediate circuits each comprising a single conductor and a ground return, means con trolled from the train for completing a circuit including an intermediate circuit and said line to connect said two telephone sets, and means controlledfrom the train for connecting a plurality of said intermediate circuits together independently of said line.

18. In a system forcommunicating between 1 a moving train and a wayside point, the combination, with a communication set at the wayside point, of a'line extending from said set along the routefollowed by the train, a communication set on the train, a plurality of intermediate circuits each comprising a single conductor and a ground return and adapted to be inductively connected with the set on the train, and means controlled from either the train or the wayside point for connecting an intermediate circuit to said line to complete a communicatingcircuit between said two sets. V

19. In a system for communicating between two stations on a moving train or between either of said stations and a wayside station, a communication set at each station, a line extending from the wayside station along the route vfollowed by the train, a plurality of intermediate circuits each comprising'a single conductor and a ground return and adapted tobe inductively connected with the sets on the train, means for connecting certain of said circuits to saidline to establish communication between a station in the train and the wayside station, and means for connecting certain of said circuits together independently of said line to establish communication between the stations on the train.

In witness whereof, I hereunto subscribe my name this 27th day of June, A. D. 1930.

WILLIAM C. PHEBUS. 

